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Now that my rust skills have been honed, I noticed that there's a lot of
generics in our gem bindings that don't actually need to be here. Currently
the hierarchy of traits in our gem bindings looks like this:
* Drivers implement:
* BaseDriverObject<T: DriverObject> (has the callbacks)
* DriverObject (has the drm::Driver type)
* Crate implements:
* IntoGEMObject for Object<T> where T: DriverObject
Handles conversion to/from raw object pointers
* BaseObject for T where T: IntoGEMObject
Provides methods common to all gem interfaces
Also of note, this leaves us with two different drm::Driver associated
types:
* DriverObject::Driver
* IntoGEMObject::Driver
I'm not entirely sure of the original intent here unfortunately (if anyone
is, please let me know!), but my guess is that the idea would be that some
objects can implement IntoGEMObject using a different ::Driver than
DriverObject - presumably to enable the usage of gem objects from different
drivers. A reasonable usecase of course.
However - if I'm not mistaken, I don't think that this is actually how
things would go in practice. Driver implementations are of course
implemented by their associated drivers, and generally drivers are not
linked to each-other when building the kernel. Which is to say that even in
a situation where we would theoretically deal with gem objects from another
driver, we still wouldn't have access to its drm::driver::Driver
implementation. It's more likely we would simply want a variant of gem
objects in such a situation that have no association with a
drm::driver::Driver type.
Taking that into consideration, we can assume the following:
* Anything that implements BaseDriverObject will implement DriverObject
In other words, all BaseDriverObjects indirectly have an associated
::Driver type - so the two traits can be combined into one with no
generics.
* Not everything that implements IntoGEMObject will have an associated
::Driver, and that's OK.
And with this, we now can do quite a bit of cleanup with the use of
generics here. As such, this commit:
* Removes the generics on BaseDriverObject
* Moves DriverObject::Driver into BaseDriverObject
* Removes DriverObject
* Removes IntoGEMObject::Driver
* Add AllocImpl::Driver, which we can use as a binding to figure out the
correct File type for BaseObject
Leaving us with a simpler trait hierarchy that now looks like this:
* Drivers implement: BaseDriverObject
* Crate implements:
* IntoGEMObject for Object<T> where T: DriverObject
* BaseObject for T where T: IntoGEMObject
Which makes the code a lot easier to understand and build on :).
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250908185239.135849-2-lyude@redhat.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
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